Have 99 Fleetwood Discover, 34 ft. I was parked at a curb for 2 days
I put the rt rear jack down only. Today I notice that the frig was coming
Out the wall. I was able Tried push it back, but it's not secure. How
Is it firmed up? Do I have to take to RV shop or can I lock it down.
I apologize if format is not easy to read as it is post with my phone

There should be a couple of screws in the base at the back (outside) access. Look for the frame tracks on the bottom of the fridge. There should be holes in the tracks where the screws are normally installed.